curing-material

# Curing Material Setup ## Description Define UMAT material for composite curing and elastic material for mold. Invoke when user needs COM material with UMAT subroutine, TOOL material, or material constants for curing simulation. ## COM Material (Composite) The composite material uses a user-defined material (UMAT) subroutine to model the curing behavior, including cure kinetics, glass transition, and orthotropic thermal expansion. ``` *Material, name=COM *Depvar 4, *Expansion, type=ORTHO, user *User Material, constants=1 1., ``` ### Keyword Details - **\*Depvar**: Defines 4 state variables (SDV1-SDV4) that track the curing state throughout the analysis. - **\*Expansion, type=ORTHO, user**: User-defined orthotropic thermal expansion. The expansion coefficients are computed inside the UMAT subroutine based on the current curing state and temperature. - **\*User Material, constants=1**: A single material constant is passed to the UMAT subroutine (value=1.0). This constant is used as a flag or scaling factor within the subroutine logic. ### UMAT Subroutine - The UMAT file (`Threestep.for`) must be provided at job submission. - The subroutine implements the three-step curing model (viscous, rubbery, glassy states). - The UMAT uses temperature and state variables to determine the current material state and compute the Jacobian, stress, and state variable updates. ### How to Attach UMAT The UMAT subroutine is attached to the job via the `userSubroutine` argument when creating the job from an input file: ```python mdb.JobFromInputFile( name='curing_job', inputFileName='curing.inp', userSubroutine=umat_path ) ``` Where `umat_path` is the absolute path to the `Threestep.for` file. ### State Variables Meaning The 4 state variables (SDV1-SDV4) track the curing state: - **SDV1**: Degree of cure (alpha) - ranges from 0 (uncured) to 1 (fully cured) - **SDV2**: Glass transition temperature (Tg) - evolves with degree of cure - **SDV3**: Current material state indicator (viscous/rubbery/glassy) - **SDV4**: Additional curing parameter (e.g., residual cure strain or volumetric shrinkage) These state variables are updated at each increment by the UMAT subroutine and can be monitored through field output requests. ## TOOL Material (Mold) The mold material is modeled as a standard linear elastic material with isotropic thermal expansion. ``` *Material, name=TOOL *Elastic 69000., 0.33 *Expansion 2.52e-05, ``` ### Keyword Details - **\*Elastic**: Isotropic linear elasticity. - Young's modulus E = 69000 MPa (69 GPa, typical aluminum mold) - Poisson's ratio nu = 0.33 - **\*Expansion**: Isotropic thermal expansion coefficient = 2.52e-05 /°C The mold material does not require a UMAT subroutine since it behaves as a standard elastic solid throughout the curing cycle. Its thermal expansion contributes to the contact interaction and stress transfer to the composite during heating and cooling. ## Notes - The COM material requires the UMAT subroutine to function; without it, the analysis will fail. - The TOOL material uses built-in Abaqus material models and does not require any subroutine. - Material constants and expansion coefficients should be verified against the specific composite system and mold material being used. - The UMAT subroutine name (`Threestep.for`) refers to the three-step curing model (viscous, rubbery, glassy).